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  • Country
  • Subregion Name
  • Primary Volcano Type
  • Last Known Eruption
  • 43.572°N
  • 144.561°E

  • 857 m
    2811 ft

  • 285081
  • Latitude
  • Longitude

  • Summit

  • Volcano

There are no activity reports for Mashu.

 Available Weekly Reports

There are no Weekly Reports available for Mashu.

Summary of eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1080 ± 100 years Unknown Confirmed 5 Radiocarbon (corrected) Kamuinupuri, Tephra layer Ma-b
0350 ± 100 years Unknown Confirmed 2 Radiocarbon (corrected) Kamuinupuri, Tephra layer Ma-c1
0150 ± 100 years Unknown Confirmed 4 Radiocarbon (corrected) Kamuinupuri, Tephra layers Ma-c4-c2
2050 BCE ± 40 years Unknown Confirmed 4 Radiocarbon (corrected) Kamuinupuri, Tephra layer Ma-d
2800 BCE ± 1000 years Unknown Confirmed 3 Tephrochronology Kamuinupuri, Tephra layer Ma-e'
3550 BCE ± 40 years Unknown Confirmed 4 Radiocarbon (corrected) Kamuinupuri, Tephra layer Ma-e
5550 BCE ± 100 years Unknown Confirmed 6 Radiocarbon (corrected) Tephra layers Ma-j-f

The following references are the sources used for data regarding this volcano. References are linked directly to our volcano data file. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title. Additional discussion of data sources can be found under Volcano Data Criteria.

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior..

Japan Meteorological Agency, 1975. National Catalogue of the Active Volcanoes in Japan. Tokyo: Japan Meteorological Agency, 119 p (in Japanese).

Japan Meteorological Agency, 1996. National Catalogue of the Active Volcanoes in Japan (second edition). Tokyo: Japan Meteorological Agency, 502 p (in Japanese).

Japan Meteorological Agency, 2013. National Catalogue of the Active Volcanoes in Japan (fourth edition, English version). Japan Meteorological Agency.

Katsui Y, Ando S, Inaba K, 1975. Formation and magmatic evolution of Mashu volcano, east Hokkaido, Japan. Hokkaido Univ Fac Sci Jour, 16: 533-552.

Kishimoto H, Hasegawa T, Nakagawa M, Wada K, 2009. Tephrostratigraphy and eruption style of Mashu volcano, during the last 14,000 years, eastern Hokkaido, Japan. Bull Volc Soc Japan (Kazan), 54: 15-36 (in Japanese with English abs).

Kudo T, Hoshizumi H, 2006-. Catalog of eruptive events within the last 10,000 years in Japan, database of Japanese active volcanoes. Geol Surv Japan, AIST,

Nakano S, Yamamoto T, Iwaya T, Itoh J, Takada A, 2001-. Quaternary Volcanoes of Japan. Geol Surv Japan, AIST,

Mashu is a 6-km-wide Holocene caldera that truncates a stratovolcano constructed on the ESE rim of the large Kutcharo caldera. The steep-walled caldera, filled by the remarkably transparent waters of Lake Mashu, is one of the scenic highlights of Hokkaido. Following caldera collapse about 7000 years ago, a small andesitic stratovolcano, Kamuinupuri, was formed beginning about 4000 years ago, creating a reentrant into the SE side of the deep caldera lake. A large explosive eruption about 1000 years ago, the latest dated eruption, created a 1.2 x 1.5 km crater at the summit of Kamuinupuri. The small island of Kamuishu in the center of Lake Mashu represents the tip of a mostly submerged dacitic lava dome.